But it isn't simply a matter of getting some calories down. According to research published in 2003, kids breakfasting on fizzy drinks and sugary snacks performed at the level of an average 70-year-old in tests of memory and attention. Beans on toast is a far better combination, as Barbara Stewart from the University of Ulster, UK, discovered. Toast alone boosted children's scores on a variety of cognitive tests, but when the tests got tougher, the breakfast with the high-protein beans worked best. Beans are also a good source of fibre, and other research has shown a link between a high-fibre diet and improved cognition. If you can't stomach beans before midday, wholemeal toast with Marmite makes a great alternative. The yeast extract is packed with B vitamins, whose brain-boosting powers have been demonstrated in many studies.

A smart choice for lunch is omelette and salad. Eggs are rich in choline, which your body uses to produce the neurotransmitter acetylcholine. Researchers at Boston University found that when healthy young adults were given the drug scopolamine, which blocks acetylcholine receptors in the brain, it significantly reduced their ability to remember word pairs. Low levels of acetylcholine are also associated with Alzheimer's disease, and some studies suggest that boosting dietary intake may slow age-related memory loss.

A salad packed full of antioxidants, including beta-carotene and vitamins C and E, should also help keep an ageing brain in tip-top condition by helping to mop up damaging free radicals. Dwight Tapp and colleagues from the University of California at Irvine found that a diet high in antioxidants improved the cognitive skills of 39 ageing beagles - proving that you can teach an old dog new tricks.

Round off lunch with a yogurt dessert, and you should be alert and ready to face the stresses of the afternoon. That's because yogurt contains the amino acid tyrosine, needed for the production of the neurotransmitters dopamine and noradrenalin, among others. Studies by the US military indicate that tyrosine becomes depleted when we are under stress and that supplementing your intake can improve alertness and memory.

Don't forget to snaffle a snack mid-afternoon, to maintain your glucose levels. Just make sure you avoid junk food, and especially highly processed goodies such as cakes, pastries and biscuits, which contain trans-fatty acids. These not only pile on the pounds, but are implicated in a slew of serious mental disorders, from dyslexia and ADHD (attention deficit hyperactivity disorder) to autism. Hard evidence for this is still thin on the ground, but last year researchers at the annual Society for Neuroscience meeting in San Diego, California, reported that rats and mice raised on the rodent equivalent of junk food struggled to find their way around a maze, and took longer to remember solutions to problems they had already solved.

It seems that some of the damage may be mediated through triglyceride, a cholesterol-like substance found at high levels in rodents fed on trans-fats. When the researchers gave these rats a drug to bring triglyceride levels down again, the animals' performance on the memory tasks improved.

Brains are around 60 per cent fat, so if trans-fats clog up the system, what should you eat to keep it well oiled? Evidence is mounting in favour of omega-3 fatty acids, in particular docosahexaenoic acid or DHA. In other words, your granny was right: fish is the best brain food. Not only will it feed and lubricate a developing brain, DHA also seems to help stave off dementia. Studies published last year reveal that older mice from a strain genetically altered to develop Alzheimer's had 70 per cent less of the amyloid plaques associated with the disease when fed on a high-DHA diet.

Finally, you could do worse than finish off your evening meal with strawberries and blueberries. Rats fed on these fruits have shown improved coordination, concentration and short-term memory. And even if they don't work such wonders in people, they still taste fantastic. So what have you got to lose?

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Music may tune up your thinking, but you can't just crank up the volume and expect to become a genius

A DECADE ago Frances Rauscher, a psychologist now at the University of Wisconsin at Oshkosh, and her colleagues made waves with the discovery that listening to Mozart improved people's mathematical and spatial reasoning. Even rats ran mazes faster and more accurately after hearing Mozart than after white noise or music by the minimalist composer Philip Glass. Last year, Rauscher reported that, for rats at least, a Mozart piano sonata seems to stimulate activity in three genes involved in nerve-cell signalling in the brain.

This sounds like the most harmonious way to tune up your mental faculties. But before you grab the CDs, hear this note of caution. Not everyone who has looked for the Mozart effect has found it. What's more, even its proponents tend to think that music boosts brain power simply because it makes listeners feel better - relaxed and stimulated at the same time - and that a comparable stimulus might do just as well. In fact, one study found that listening to a story gave a similar performance boost.

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